Guest session cwd and command preflight helpers were emitting literal
`\\n` separators, so the guest shell saw malformed one-line scripts and
could fail `preflight_cwd` even when `/root/repo` already existed.
Replace those builders with real newlines, and fix the nearby attach
helper commands that were making the same mistake.
Add a small daemon guest-SSH seam so workspace preparation and session
start can share a fake backend in tests, then cover the regression with
an end-to-end daemon test for `PrepareVMWorkspace` followed by
`StartGuestSession` on `/root/repo`.
Validation: `GOCACHE=/tmp/banger-gocache go test ./internal/daemon` and
`GOCACHE=/tmp/banger-gocache go test ./...`.
Add daemon-backed workspace and guest-session primitives so host
orchestrators can prepare /root/repo, launch long-lived guest commands,
and attach to pipe-mode sessions over the local stdio mux bridge.
Persist richer session metadata and launch diagnostics, preflight guest
cwd/command requirements, make pipe-mode attach rehydratable from guest
state after daemon restart, and allow submodules when workspace prepare
runs in full_copy mode.
At the same time, stop vm run from auto-attaching opencode, make it
print next-step commands instead, and make glibc guest images more
agent-ready by installing node, opencode, claude, and pi while syncing
opencode/claude/pi auth files into work disks on VM start.
Validation:
- GOCACHE=/tmp/banger-gocache go test ./...
- make build
- banger vm workspace prepare --help
- banger vm session --help
- banger vm session start --help
- banger vm session attach --help
